This invention relates generally to particle sensitive or radiation sensitive systems for detecting, measuring or controlling particles and/or radiation, and is concerned with the manipulation of particle flow though a small aperture in order to accomplish accurate measurement of particle flow for example, and/or detailed control of reactions, translocation and aggregation of materials.
The ability to control the transport of nano-scaled particles and to determine the characteristics of such particles has utility in the fields of molecular biology, biochemistry, biotechnology, genetics, medicine and nano-scale technologies.
DuBlois and Wesley, in “Sizes and Concentrations of Several Type C Oncornaviruses and Bacteriophage T2 by the Resistive-Pulse Technique”, JOURNAL OF VIROLOGY, August 1977, p. 227-233, describe a Nanopar counter, that is a Coulter counter adapted to measure nanoscale particles. This counter has the ability to electrophoretically measure the quantity of particles of a certain size that travel though an aperture under the effect of voltage and pressure differentials across the aperture. However, the described device lacks the ability to selectively change the voltage and pressure over the aperture in order to control the velocity and displacement of particles and therefore increase the sensitivity of the instrument or allow for individual particle displacement control.
U.S. Pat. No. 6,004,443 teaches a method for controlling sample dispersion in a separation column during free-fluid electrophoresis in a capillary by detecting sample dispersion and correcting the dispersion by instituting an imbalance between pressure induced flow and electroosmotic flow. This improved method of capillary electrophoresis allows for the exact control of particles in capillary, which has advantage in that medium will be optimally separated in the capillary. However the separation of particles is not from one reservoir to another, and furthermore there is no proposal to diffuse particles from one reservoir to another. Also, the control of particles for aggregation or reaction in one reservoir is not achieved by this method.
U.S. Pat. No. 7,279,883 discloses an innovative miniature Coulter counter that is manufactured utilizing microfabrication techniques. The counter incorporates a micro- or nano-fluidic system to force particles though the conduits of the device so that the impedance of the device will alter according to the nature of the particles and enable the measurement of the particles. The manufacturing technique allows for multiple size conduits to be employed simultaneously on a sample, thereby allowing for the detection of many different particles in one solution. However the device does not allow for the exact control of induced or electroosmotic flow of particles, and is therefore limited in its application to the detection of particles.
U.S. Pat. No. 7,077,939 discloses a method for particle control and detection utilizing the combination of electrophoresis and pressure over a single nanotube embedded in a membrane. However the method does not allow for the real time adjustment of both pressure and current in order to exactly control the velocity and displacement of particles. Also, the use of carbon nanotubes as apertures for the electrical detection of particles influences the measurement. A carbon nanontube by nature has high electrical conductivity and as such dominates the electrical properties of the aperture that it forms. Therefore the small change in the electrical properties of the aperture when a particle travels though it are masked by the presence of the carbon nanotube.
U.S. Pat. No. 4,331,862 teaches a method for calibrating blood particle counters utilizing particles of different sizes and concentrations at different flow rates. However the calibration method does not include control of the variables of electrical potential and aperture size. The method is therefore limited in its application to processes where flow rate, particle size and particle concentration are the only variables that can be altered.
PCT/EP2005/053366 discloses an adjustable elastomeric aperture that can be adjusted for the purpose of detecting, measuring and controlling particles and/or electromagnetic radiation. The disclosed device is most typically fabricated by penetration of sheets of elastomeric material pre-cut into cruciform geometries.
It is an object of the invention to overcome disadvantages of prior systems by combining electrical potential and pressure differential across an aperture in order to create precise control of nano-scale particle movement in micro- and nano-fluidic applications.